Former President George W. Bush sat stone-faced in an elementary school classroom for several minutes after learning the U.S. was under attack on 9/11 because he wanted to “project a sense of calm," he says in an interview for The National Geographic Channel. "My first reaction was anger. Who the hell would do that to America?” Bush explains. “Then I immediately focused on the children, and the contrast between the attack and the innocence of children.” Bush said he didn’t want to “rattle” the kids by leaving abruptly after his chief of staff whispered that a second plane had hit the World Trade Tower and America was under attack. “I had been in enough crises to know that the first thing a leader has to do is to project calm," Bush says in the interview to mark the 10th anniversary of the 9/11 attacks. The piece airs Aug. 28.